Reproductive and developmental toxicity of formaldehyde: a systematic review

Distinct DNA repair mechanisms prevent formaldehyde toxicity during development, reproduction and aging

Formaldehyde (FA) is a recognized environmental and metabolic toxin implicated in cancer development and aging. Inherited mutations in the FA-detoxifying enzymes ADH5 and ALDH2 genes lead to FA overload in the severe multisystem AMeD syndrome. FA accumulation causes genome damage including DNA-protein-, inter- and intra-strand crosslinks and oxidative lesions. However, the influence of distinct DNA repair systems on organismal FA resistance remains elusive. We have here investigated the consequence of a range of DNA repair mutants in a model of endogenous FA overload generated by downregulating the orthologs of human ADH5 and ALDH2 in C. elegans. We have focused on the distinct components of nucleotide excision repair (NER) during developmental growth, reproduction and aging. Our results reveal three distinct modes of repair of FA-induced DNA damage: Transcription-coupled repair (TCR) operating NER-independently during developmental growth or through NER during adulthood, and, in concert with global-genome (GG-) NER, in the germline and early embryonic development. Additionally, we show that the Cockayne syndrome B (CSB) factor is involved in the resolution of FA-induced DNA-protein crosslinks, and that the antioxidant and FA quencher N-acetyl-l-cysteine (NAC) reverses the sensitivity of detoxification and DNA repair defects during development, suggesting a therapeutic intervention to revert FA-pathogenic consequences.

A Review on the Current State of Microcapsule-Based Self-Healing Dental Composites

Resin-based dental composites, commonly used in dentistry, offer several advantages including minimally invasive application, esthetically pleasing appearance, and good physical and mechanical properties. However, these dental composites can be susceptible to microcracks due to various factors in the complex oral environment. These microcracks can potentially lead to clinical restoration failure. Conventional materials and methods are inadequate for detecting and repairing these microcracks in situ. Consequently, incorporating self-healing properties into dental composites has become a necessity. Recent years have witnessed rapid advancements in self-healing polymer materials, drawing inspiration from biological bionics. Microcapsule-based self-healing dental composites (SHDCs) represent some of the most prevalent types of self-healing materials utilized in this domain. In this article, we undertake a comprehensive review of the most recent literature, highlighting key insights and findings related to microcapsule-based SHDCs. Our discussion centers particularly on the preparation techniques, application methods, and the promising future of self-healing microcapsules in the field of dentistry.

A systematic review on the role of biosecurity to prevent or control colibacillosis in broiler production

This systematic review aimed at investigating the role that biosecurity can have in preventing or controlling colibacillosis in broiler production. Primary studies with natural or experimental exposure to avian pathogenic Escherichia coli, evaluating any biosecurity measure to prevent or control colibacillosis in broiler chickens with at least one of the following outcomes: feed conversion ratio (FCR), condemnations at slaughter, and mortality due to colibacillosis, were included. A systematic search was carried out in 4 databases according to the Cochrane handbook and reported following the PRISMA 2020 directions. Studies (n = 3,886) were screened in a 2-phase process and data matching the inclusion criteria were extracted. Risk of bias assessment was performed. Four studies reporting biosecurity measures to prevent or control colibacillosis in broiler production were included. In all studies, only disinfection during either the pre-hatching period (n = 3) or the post-hatching period (n = 1) was evaluated as biosecurity measure in broiler production, as well as its effect on FCR (n = 2) and mortality (n = 4) due to colibacillosis. No studies with effects on condemnations at slaughter were found. Due to the heterogeneity of studies in regard to interventions and outcomes, meta-analysis was not carried out. The limited findings of this systematic review do not provide a comprehensive evidence to statistically evaluate the efficacy of biosecurity to prevent or control colibacillosis in broiler production. The scarcity of evidence found suggests that further and deeper investigations on the topic are needed, considering the variety of interventions related to biosecurity.

What are the DNA lesions underlying formaldehyde toxicity?

Formaldehyde is a highly reactive organic compound. Humans can be exposed to exogenous sources of formaldehyde, but formaldehyde is also produced endogenously as a byproduct of cellular metabolism. Because formaldehyde can react with DNA, it is considered a major endogenous source of DNA damage. However, the nature of the lesions underlying formaldehyde toxicity in cells remains vastly unknown. Here, we review the current knowledge of the different types of nucleic acid lesions that are induced by formaldehyde and describe the repair pathways known to counteract formaldehyde toxicity. Taking this knowledge together, we discuss and speculate on the predominant lesions generated by formaldehyde, which underly its natural toxicity.

Revolutionizing poultry hygiene: advanced electrostatic and cold fog disinfection strategies combat Mycoplasma gallisepticum in hatching eggs

The incidence of chronic respiratory disease (CRD) due to Mycoplasma gallisepticum (MG) contamination in hatching eggs poses a serious threat to poultry health and hatchability. Implementing effective sanitization methods while safeguarding the hatching potential of embryos is crucial. This study aimed to explore novel techniques for sanitizing hatching-fertile eggs to prevent and manage MG-associated CRD. The primary objective was to assess the efficacy of acidic electrochemically stimulated water (ECS), focusing on MG disinfection. Additionally, the study investigated 2 application methods, 1) electrostatic disinfection (ED) and 2) cold fog (CF) disinfection, to evaluate their bactericidal effects against MG-contaminated eggs. Deliberately infected MG strains were used for the experimental design, which compared the disinfection efficacy of ECS with its acidic properties. The comparison involved ED, which applies an electrostatic charge to water particles, and CF disinfection, a cold mist technique. Both methods aimed to target MG without compromising egg-hatching potential. The results indicated a significant (p < 0.05) reduction in colony-forming units per milliliter (CFU/mL). However, both application methods demonstrated distinct bactericidal effects. Eggs treated with electrostatic disinfection showed a significant (p < 0.001) reduction in embryonic mortality during incubation (10%) compared to control untreated eggs (18%). Similarly, the CF method exhibited a significant (p < 0.001) decrease in embryonic mortality (13%). The ECS potential in reducing embryonic mortality within the pH range of 2.5 to 6.5 was noted. Both the ED and CF methods show promise for preventing MG-induced hatchery infection while maintaining egg-hatching potential. This study presents innovative techniques to control MG in hatching eggs, contributing to improved poultry health and reduced CRD incidence.

Tobacco or marijuana use and infertility: a committee opinion

In the United States, approximately 21% of adults report some form of tobacco use, although 18% report marijuana use. Although the negative impact of tobacco use in pregnancy is well documented, the impact of tobacco and marijuana on fertility and reproduction is less clear. This committee opinion reviews the potential deleterious effects of tobacco, nicotine, and marijuana use on conception, ovarian follicular dynamics, sperm parameters, gamete mutations, early pregnancy, and assisted reproductive technology outcomes. It also reviews the current status of tobacco smoking cessation strategies. This document replaces the 2018 American Society for Reproductive Medicine Practice Committee document entitled Smoking and Infertility: a committee opinion (Fertil Steril 2018).

Enhanced antibacterial activity of porous chitosan-based hydrogels crosslinked with gelatin and metal ions

Addressing the increasing drug resistance in pathogenic microbes, a significant threat to public health, calls for the development of innovative antibacterial agents with versatile capabilities. To enhance the antimicrobial activity of non-toxic biomaterials in this regard, this study focuses on novel, cost-effective chitosan (CS)-based hydrogels, crosslinked using gelatin (GEL), formaldehyde, and metallic salts (Ag+, Cu2+, and Zn2+). These hydrogels are formed by mixing CS and GEL with formaldehyde, creating iminium ion crosslinks with metallic salts without hazardous crosslinkers. Characterization techniques like FTIR, XRD, FESEM, EDX, and rheological tests were employed. FTIR analysis showed metal ions binding to amino and hydroxyl groups on CS, enhancing hydrogelation. FESEM revealed that freeze-dried hydrogels possess a crosslinked, porous structure influenced by various metal ions. Antibacterial testing against gram-negative and gram-positive bacteria demonstrated significant bacterial growth inhibition. CS-based hydrogels containing metal ions showed reduced MIC and MBC values against Staphylococcus aureus (0.5, 8, 16 µg/mL) and Escherichia coli (1, 16, 8 µg/mL) for CS-g-GEL-Ag+, CS-g-GEL-Cu2+, and CS-g-GEL-Zn2+. MTT assay results confirmed high biocompatibility (84.27%, 85.24%, 84.96% viability at 10 µg/mL) for CS-based hydrogels towards HFF-1 cells over 48 h. Therefore, due to their non-toxic nature, these CS hydrogels are promising for antibacterial applications.

Genetic and environmental factors driving congenital solitary functioning kidney

BACKGROUND

Congenital solitary functioning kidney (CSFK) is an anomaly predisposing to hypertension, albuminuria and chronic kidney disease. Its aetiology is complex and includes genetic and environmental factors. The role of gene-environment interactions (G×E), although relevant for other congenital anomalies, has not yet been investigated. Therefore, we performed a genome-wide G×E analysis with six preselected environmental factors to explore the role of these interactions in the aetiology of CSFK.

METHODS

In the AGORA (Aetiologic research into Genetic and Occupational/environmental Risk factors for Anomalies in children) data- and biobank, genome-wide single-nucleotide variant (SNV) data and questionnaire data on prenatal exposure to environmental risk factors were available for 381 CSFK patients and 598 healthy controls. Using a two-step strategy, we first selected independent significant SNVs associated with one of the six environmental risk factors. These SNVs were subsequently tested in G×E analyses using logistic regression models, with Bonferroni-corrected P-value thresholds based on the number of SNVs selected in step one.

RESULTS

In step one, 7-40 SNVs were selected per environmental factor, of which only rs3098698 reached statistical significance (P = .0016, Bonferroni-corrected threshold 0.0045) for interaction in step two. The interaction between maternal overweight and this SNV, which results in lower expression of the Arylsulfatase B (ARSB) gene, could be explained by lower insulin receptor activity in children heterozygous for rs3098698. Eight other G×E interactions had a P-value <.05, of which two were biologically plausible and warrant further study.

CONCLUSIONS

Interactions between genetic and environmental factors may contribute to the aetiology of CSFK. To better determine their role, large studies combining data on genetic and environmental risk factors are warranted.

Synthesis and characterisation of microcapsules for self-healing dental resin composites

AIM

The purpose of this study was to i) synthesise TEGDMA-DHEPT microcapsules in a laboratory setting; ii) characterise the resultant microcapsules for quality measures.

MATERIALS & METHODS

Microcapsules were prepared by in situ polymerization of PUF shells. Microcapsules characterisation include size analysis, optical and SEM microscopy to measure the diameter and analyse the morphology of PUF microcapsules. FT-IR spectrometer evaluated microcapsules and benzyl peroxide catalyst polymerization independently.

RESULT

Average diameter of TEGDMA-DHEPT microcapsules was 120 ± 45 μm (n: 100). SEM imaging of the capsular shell revealed a smooth outer surface with deposits of PUF nanoparticles that facilitate resin matrix retention to the microcapsules upon composite fracture. FT-IR spectra showed that microcapsules crushed with BPO catalyst had degree of conversion reached to 60.3%.

CONCLUSION

TEGDMA-DHEPT microcapsules were synthesised according to the selected parameters. The synthesised microcapsules have a self-healing potential when embedded into dental resin composite as will be demonstrated in our future work.

Incidence of lung cancer among healthcare workers in Hunan Province and analysis of related risk factors

Background

The prevalence of lung cancer, a major type of malignant tumor, has been increasing over the years greatly impacting the health of Chinese residents. This study investigates the epidemiological characteristics of lung cancer among healthcare workers in the Hunan Province, as well as the occupational risk factors.

Methods

The data analyzed in this study was collected from the largest tumor hospital in the province: the Hunan Provincial Tumor Hospital affiliated with Central South University, School of Medicine. The data collected encompasses input collected between the years of 2004 to 2013 of the population of healthcare workers who were hospitalized for lung cancer treatments. Information was obtained through statistical analysis and telephonic interviews.

Results

The prevalence of lung cancer among healthcare workers was much higher than that of the general population, as revealed by the difference between number of healthcare worker cases per 1,000 cases and number of healthcare workers per 1,000 population in the decade from 2004 to 2013. Analysis of the data further demonstrates that lung cancer prevalence among healthcare workers increases exponentially with age. Although smoking has been shown to increase the incidence of lung cancer to some extent, it is most likely not the main cause of lung cancer. In addition, it appears that the highest rates of lung cancer incidence occurs in mainly in primary general practitioners, medical radiologists, and nurses. The lack of awareness of personal safety measures may place healthcare workers at a greater risk of lung cancer.

Role and mechanism of miR-871-3p/Megf8 in regulating formaldehyde-induced cardiomyocyte inflammation and congenital heart disease

OBJECTIVE AND DESIGN

We aimed to investigate the molecular mechanism underlying formaldehyde (FA)-induced congenital heart disease (CHD) using in vitro and in vivo models.

MATERIALS AND SUBJECTS

Neonatal rat heart tissues and H9C2 cells were used for in vitro studies, while FA-exposed new-born rats were used for in vivo studies.

TREATMENT

H9C2 cells were exposed to FA concentrations of 0, 50, 100 and 150 μM/mL for 24 h.

METHODS

Whole transcriptome gene sequencing identified differentially expressed miRNAs in neonatal rat heart tissues, while Real-time quantitative PCR (RT-qPCR) assessed miR-871-3p and Megf8 expression. RNA pull-down and dual-luciferase reporter assays determined miR-871-3p and Megf8 relationships. Inflammatory cytokine expression was assessed by western blotting. A FA-induced CHD model was used to validate miR-871-3p regulatory effects in vivo.

RESULTS

We identified 89 differentially expressed miRNAs, with 28 up-regulated and 61 down-regulated (fold change ≥ 2.0, P < 0.05). Inflammation (interleukin) and signalling pathways were found to control FA-induced cardiac dysplasia. miR-871-3p was upregulated in FA-exposed heart tissues, modulated inflammation, and directly targeted Megf8. In vivo experiments showed miR-871-3p knockdown inhibited FA-induced inflammation and CHD.

CONCLUSION

We demonstrated miR-871-3p's role in FA-induced CHD by targeting Megf8, providing potential targets for CHD intervention and improved diagnosis and treatment strategies.

N-Acyloxymethyl-phthalimides deliver genotoxic formaldehyde to human cells

Formaldehyde is a pollutant and human metabolite that is toxic at high concentrations. Biological studies on formaldehyde are hindered by its high reactivity and volatility, which make it challenging to deliver quantitatively to cells. Here, we describe the development and validation of a set of N-acyloxymethyl-phthalimides as cell-relevant formaldehyde delivery agents. These esterase-sensitive compounds were similarly or less inhibitory to human cancer cell growth than free formaldehyde but the lead compound increased intracellular formaldehyde concentrations, increased cellular levels of thymidine derivatives (implying increased formaldehyde-mediated carbon metabolism), induced formation of cellular DNA-protein cross-links and induced cell death in pancreatic cancer cells. Overall, our N-acyloxymethyl-phthalimides and control compounds provide an accessible and broadly applicable chemical toolkit for formaldehyde biological research and have potential as cancer therapeutics.

GRPR down-regulation inhibits spermatogenesis through Ca2+ mediated by PLCβ/IP3R signaling pathway in long-term formaldehyde-exposed rats

Formaldehyde (FA), which is known as an air pollutant, has been proven to induce male infertility. However, the underlying mechanism of FA-induced male infertility remains elusive. In this study, 24 male SD rats were exposed to different levels of FA (0, 0.5, 2.46, and 5 mg/m3) for eight consecutive weeks. Through HE staining and sperm smear, we observed that FA exposure resulted in spermatogenic injury and the sperm quality decreased in rats. The qRT-PCR and Western blot analysis further revealed that GRPR was down-regulated in testicular tissues of FA-exposed rats as well as primary spermatogenic cells. Meanwhile, ZDOCK uncovered an interaction between GRPR and PLCβ. In addition, the CCK8, Fluo 3-AM and Flow cytometry results showed that FA exposure suppressed the expression of GRPR, PLCβ and IP3R, consequently reducing the Ca2+ concentration in spermatogenic cells, inducing apoptosis and inhibiting proliferation of spermatogenic cells. Moreover, rescue experiments confirmed that promoting GRPR could improve intracellular Ca2+ concentration by upregulating PLCβ and IP3R, partially reducing the apoptosis and promoting the proliferation of FA-treated spermatogenic cells. These findings revealed that GRPR participates in spermatogenesis through Ca2+ mediated by the PLCβ/IP3R signaling pathway in FA-exposed rats.

Serum Concentrations of Benzaldehyde, Isopentanaldehyde and Sex Hormones: Evidence from the National Health and Nutrition Examination Survey

Exposure to environmental chemicals could disturb the balance of sex hormones. However, the studies on Benzaldehyde, Isopentanaldehyde exposure and sex hormones are still limited. Based on the data of 1064 participants in the National Health and Nutrition Examination Survey (NHANES), we used the linear regression model and restricted cubic spline (RCS) model to evaluate the associations of Benzaldehyde/Isopentanaldehyde exposure with testosterone (TT), estradiol (E2), sex hormone binding globulin (SHBG), free androgen index (FAI) and the ratio of TT to E2 (TT/E2). A ln-unit increase in Benzaldehyde was associated with lower TT (β = -0.048, P = 0.030) and E2 (β = -0.094, P = 0.046) in all participants. After further adjustment for menopausal status, Benzaldehyde was negatively associated with E2 (β = -0.174, P = 0.045) in females. The interaction between Benzaldehyde and gender was significant (P_inter = 0.031). However, Isopentanaldehyde showed a positive association with SHBG and TT/E2 in all participants (all P < 0.05). The positive associations of Isopentanaldehyde with TT, SHBG and TT/E2 were found in males but not in females. RCS plots illustrated the linear associations of Benzaldehyde with E2 (P_non-linear = 0.05) in females and Isopentanaldehyde with TT (P_non-linear = 0.07) and TT/E2 (P_non-linear = 0.350) in males. The non-linear relationships were identified between Isopentanaldehyde and SHBG in males (P_non-linear = 0.035). Our findings indicated the effects of Benzaldehyde and Isopentanaldehyde exposure on sex hormones, and the effects had the gender specificity. Cohort studies and high-quality in vitro and in vivo experiments are needed to confirm the specific effects and uncover the underlying mechanisms.

The impact of operational factors on degradation of formaldehyde as a human carcinogen using Ag3 PO4 /TiO2 photocatalyst

Background: The International Agency for Research on Cancer (IARC) identified formaldehyde as a carcinogen in 2004, yet formaldehyde is widely used in health care settings and various industries. In recent years, photocatalytic oxidation has been developed as a potential technique for removing pollutants arising from organic chemical agents and consequently promoting the health indices. This study investigated the effect of operational factors in optimizing formaldehyde removal from the air using Ag₃ PO₄ /TiO₂ photocatalyst. Methods: An experimental study was designed to investigate the effect of operational factors on the efficiency of formaldehyde degradation. The variables investigated in this study include pollutant retention time, initial pollutant concentration and relative humidity. Sol-gel method was used to synthesize the nano-composite photocatalyst. An ideal experimental design was carried out based on Box-Behnken design (BBD) with response surface methodology (RSM). The sample size in this study includes all the glasses coated with Ag₃ PO₄ /TiO₂ photocatalyst. Results: The maximum formaldehyde degradation of 32% was obtained at the initial concentration of 2 ppm, 20% relative humidity, and 90 minutes of retention time. Based on the statistical results, the correlation coefficient of the present study for the impact of operational factors on formaldehyde degradation was 0.9635, which means that there is only 3.65% probability of error in the model. Conclusion: The operational factors examined in this study (retention time, relative humidity, and initial formaldehyde concentration) were significantly influential in the degradation efficiency of formaldehyde by the photocatalyst. Due to the high exposure of employees and clients of health and treatment centers to formaldehyde as a carcinogenic substance, the results of this study can be used in ventilation systems to remove environmental pollutants in health care centers and other occupational settings.

Identification of long non-coding RNA in formaldehyde-induced cardiac dysplasia in rats

Formaldehyde exposure during pregnancy can cause fetal congenital heart disease (CHD). However, the regulatory mechanism remains unclear. Studies on the biology of long non-coding RNAs (lncRNAs) show that lncRNAs can influence cardiac development and disease. However, expression patterns and regulatory mechanisms of action of lncRNAs in formaldehyde-induced CHD remain unclear. We used high-throughput sequencing strategies as a means of identifying lncRNA expression profiles in heart tissues of normal and formaldehyde-exposed newborn rats. Overall, 763 differentially expressed lncRNAs were identified, including 325 and 438 that were respectively up-regulated and down-regulated. GO and KEGG analyses indicated that the Ras and hedgehog signaling pathways may be important regulatory pathways in CHD caused by exposure to formaldehyde. A lncRNA-miRNA-mRNA co-expression network was constructed and a key miRNA, rno-miR-665, was identified. Furthermore, qRT-PCR analysis verified that the novel lncRNAs: MSTRG.27313.2, MSTRG.30629.2, MSTRG.36520.33, MSTRG.91234.1, and MSTRG.91233.9, were upregulated in the formaldehyde-exposed group. These differentially expressed lncRNAs identified during formaldehyde-induced CHD in newborn rats help explain CHD pathogenesis and provide an effective reference for diagnosing and treating CHD.

Sapropel as a Binding Material for Wood Processing Waste in the Development of Thermal Insulation Biocomposite

When developing new innovative building materials, their performance characteristics as well as their environmental friendliness are important. It is difficult to produce a fully ecological material for building envelopes, because there is a lack of ecological binding materials on the market, good binding materials are very expensive, and cheaper ones have poorer adhesive properties and performance characteristics. In this work, natural organic sapropel was used as an ecological binder. Before use, an organic sapropel was additionally mechanically activated. Its activation efficiency was evaluated on the basis of consistency and tensile strength. Sapropel activation increased its consistency from 112 to 168 mm and its tensile strength from 466 to 958 kPa. Wood processing waste was used as a filler for the thermal insulation biocomposite. Additionally, the wood waste was chopped to regulate the density and main performance properties of the biocomposite. The density of the biocomposite was also regulated using different amounts of sapropel and the degree of compaction of the composite mixture. In this work, the influence of the amount of sapropel, the level of compression of the biocomposite mixture, and the size of the wood waste particles on the thermal conductivity and compressive stress of the biocomposite was analyzed. It was found that the compression level had the greatest influence on both the compressive stress and thermal conductivity, up to 12 times and 43.3%, respectively.

Formaldehyde causes an increase in blood pressure by activating ACE/AT1R axis

Previous studies suggest some link between formaldehyde exposure and harmful cardiovascular effects. But whether exposure to formaldehyde can cause blood pressure to rise, and if so, what the underlying mechanism is, remains unclear. In this study, C57BL/6 male mice were exposed to 0.1, 0.5, 2.5 mg/m³ of gaseous formaldehyde for 4 h daily over a three-week period. The systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) and heart rate (HR) of the mice were measured by tail-cuff plethysmography, and any histopathological changes in the target organs of hypertension were investigated. The results showed that exposure to formaldehyde did cause a significant increase in blood pressure and heart rate, and resulted in varying degrees of damage to the heart, aortic vessels and kidneys. To explore the underlying mechanism, a specific inhibitor of angiotensin converting enzyme (ACE) was used to block the ACE/AT1R axis. We observed the levels of ACE and angiotensin II type 1 receptor (AT1R), as well as the bradykinin (BK) in cardiac cytoplasm. The data suggest that exposure to formaldehyde induced an increase in the expression of ACE and AT1R, and decreased the levels of BK. Strikingly, treatment with 5 mg/kg/d ACE inhibitor can attenuate the increase in blood pressure and the pathological changes caused by formaldehyde exposure. This result has improved our understanding of whether, and how, formaldehyde exposure affects the development of hypertension.

Association between aldehyde exposure and sex steroid hormones among adults

Exogenous and endogenous exposure to aldehydes is seen worldwide. Aldehydes are closely associated with human diseases, especially reproductive toxicity. However, the effect of aldehyde exposure on sex steroid hormones among adults remains uninvestigated. A total of 851 participants aged over 18 years were included in this cross-sectional analysis based on data from National Health and Nutrition Examination Survey (NHANES) 2013-2014. Serum aldehyde concentrations were quantified following an automated analytical method. Sex steroid hormones including total testosterone, estradiol, and sex hormone binding globulin (SHBG) were detected. Multivariate linear regression models, forest plots, generalized additive model (GAM), and smooth curve fitting analysis were used to assess the associations between quartiles of aldehydes and sex steroid hormones levels after adjusting for potential confounders. Butyraldehyde and propanaldehyde were found to be negatively associated with estradiol and SHBG in females and males, respectively. β values with 95% confidence intervals (95% CIs) were - 20.59 (- 38.30 to - 2.88) for Q2 vs. Q1 of butyraldehyde and - 8.13 (- 14.92 to - 1.33) and - 7.79 (- 14.91 to - 0.67) for Q2 vs. Q1 and Q4 vs. Q1 of propanaldehyde. No significant associations were observed between other aldehydes and sex hormones. In premenopausal women, isopentanaldehyde was inversely associated with serum total testosterone levels (Q4 vs. Q1: OR =  - 7.95, 95% CI: - 15.62 to - 0.27), whereas propanaldehyde was positively associated with serum estradiol concentration (Q3 vs. Q1: β = 28.88, 95% CI: 0.83 to 56.94). Compared with Q1, Q3 of isopentanaldehyde was associated with 3.53 pg/mL higher concentration of estradiol in postmenopausal women (β = 3.53, 95% CI: 0.08 to 6.97). Moreover, in males under 40 years, butyraldehyde and heptanaldehyde were inversely proportional to total testosterone levels and heptanaldehyde and butyraldehyde were negatively associated with estradiol and SHBG. Decreased total testosterone, elevated estradiol, and decreased SHBG levels were found in higher quartiles of benzaldehyde, hexanaldehyde and isopentanaldehyde, and propanaldehyde, respectively, in males aged over 60 years. In male participants aged 40-60 years, only hexanaldehyde was observed to be correlated with higher serum estradiol levels. In conclusion, our current research presented the association between six serum aldehydes and sex hormones. Of note, stratification analyses were conducted in participants with different menopausal statuses and age among males and females. Sex- and age-specific effect of aldehyde exposure on alterations in sex hormone levels were observed. Further studies are warranted to confirm the causal relationship and explore the underlying mechanisms.

Effect of Formaldehyde and Curcumin on Histomorphological Indices, Gene Expression Associated with Ovarian Follicular Development, and Total Antioxidant to Oxidant Levels in Wistar Rats

The present experimental study was undertaken to investigate the effect of formaldehyde (FA) and curcumin (CUR) on histomorphological features, antioxidant potential, and messenger ribonucleic acid (mRNA) levels of genes related to follicular development in FA-exposed rats. 24 Wistar female rats were divided into four study groups and given intraperitoneal injections of FA (10 mg/kg) (N = 6), FA (10 mg/kg) + CUR (100 mg/kg) (N = 6), sham (N = 6), and control (N = 6) for 14 days. Ovarian follicular histology, the related gene expression, blood factors, and anti/oxidation potentials were assessed using ovarian tissue and serum, respectively. The klotho was significantly overexpressed in the FA group compared with controls and shams. Contradictory, the factor in germ line alpha was significantly down-regulated in FA and FA + CUR groups compared to shams and controls. A significant decline was seen in the number of ovarian follicles in the FA group, independent of the developmental stage. Regarding the comparison of the FA + CUR group to other groups, a significant change was seen in the number of secondary, graafian, and atretic follicles. The FA group demonstrated significantly lower hemoglobin, red blood cell count, hematocrit, and mean corpuscular hemoglobin concentration than controls. The activity of glutathione peroxidase increased significantly in the FA group than in the controls. Despite the deleterious effects of FA on histological and molecular aspects of rat ovarian follicles, CUR does not appear to have a protective effect against the hazardous effects of this chemical. However, CUR in some cases has positive effects such as reducing follicular destruction and interstitial edema.

Formaldehyde reacts with N-terminal proline residues to give bicyclic aminals

Formaldehyde (HCHO) is a potent electrophile that is toxic above threshold levels, but which is also produced in the nuclei of eukaryotic cells by demethylases. We report studies with the four canonical human histones revealing that histone H2B reacts with HCHO, including as generated by a histone demethylase, to give a stable product. NMR studies show that HCHO reacts with the N-terminal proline and associated amide of H2B to give a 5,5-bicyclic aminal that is relatively stable to competition with HCHO scavengers. While the roles of histone modification by this reaction require further investigation, we demonstrated the potential of N-terminal aminal formation to modulate protein function by conducting biochemical and cellular studies on the effects of HCHO on catalysis by 4-oxalocrotonate tautomerase, which employs a nucleophilic N-terminal proline. The results suggest that reactions of N-terminal residues with HCHO and other aldehydes have potential to alter protein function.

Environmental Exposures and Anti-Müllerian Hormone: A Mixture Analysis in the Nurses' Health Study II

BACKGROUND

Previous studies have linked environmental exposures with anti-Müllerian hormone (AMH), a marker of ovarian reserve. However, associations with multiple environment factors has to our knowledge not been addressed.

METHODS

We included a total of 2,447 premenopausal women in the Nurses' Health Study II (NHSII) who provided blood samples during 1996-1999. We selected environmental exposures linked previously with reproductive outcomes that had measurement data available in NHSII, including greenness, particulate matter, noise, outdoor light at night, ultraviolet radiation, and six hazardous air pollutants (1,3-butadiene, benzene, diesel particulate matter, formaldehyde, methylene chloride, and tetrachloroethylene). For these, we calculated cumulative averages from enrollment (1989) to blood draw and estimated associations with AMH in adjusted single-exposure models, principal component analysis (PCA), and hierarchical Bayesian kernel machine regression (BKMR).

RESULTS

Single-exposure models showed negative associations of AMH with benzene (percentage reduction in AMH per interquartile range [IQR] increase = 5.5%, 95% confidence interval [CI] = 1.0, 9.8) and formaldehyde (6.1%, 95% CI = 1.6, 10). PCA identified four major exposure patterns but only one with high exposure to air pollutants and light at night was associated with lower AMH. Hierarchical BKMR pointed to benzene, formaldehyde, and greenness and suggested an inverse joint association with AMH (percentage reduction comparing all exposures at the 75th percentile to median = 8.2%, 95% CI = 0.7, 15.1). Observed associations were mainly among women above age 40.

CONCLUSIONS

We found exposure to benzene and formaldehyde to be consistently associated with lower AMH levels. The associations among older women are consistent with the hypothesis that environmental exposures accelerate reproductive aging.

E-cigarette vapor exposure in utero causes long-term pulmonary effects in offspring

The in utero environment is sensitive to toxicant exposure, altering the health and growth of the fetus, and thus sensitive to contaminant exposure. Though recent clinical data suggest that e-cigarette use does no further harm to birth outcomes than a nicotine patch, this does not account for the effects of vaping during pregnancy on the long-term health of offspring. Pregnant mice were exposed to: 1) e-cigarette vapor with nicotine (PV + Nic; 2% Nic in 50:50 propylene glycol: vegetable glycerin), 2) e-cigarette vapor without nicotine [PV; (50:50 propylene glycol:vegetable glycerin)], or 3) HEPA filtered air (FA). Dams were removed from exposure upon giving birth. At 5 mo of age, pulmonary function tests on the offspring revealed female and male mice from the PV group had greater lung stiffness (Ers) and alveolar stiffness (H) compared with the FA group. Furthermore, baseline compliance (Crs) was reduced in female mice from the PV group and in male mice from the PV and PV + Nic groups. Lastly, female mice had decreased forced expiratory volume (FEV0.1) in the PV group, but not in the male groups, compared with the FA group. Lung histology revealed increased collagen deposition around the vessels/airways and in alveolar tissue in PV and PV + Nic groups. Furthermore, goblet hyperplasia was observed in PV male and PV/PV + Nic female mice. Our work shows that in utero exposure to e-cigarette vapor, regardless of nicotine presence, causes lung dysfunction and structural impairments that persist in the offspring to adulthood.

Impact of disinfectants on the intestinal bacterial symbionts and immunity of silkworm (Bombyx mori L.)

The insect egg surface can serve as a vehicle for vertical symbiont transmission from the maternal parent to its offspring. Hypochlorite and formaldehyde are two common disinfectants used for insect egg surface sterilization. Here, we explored the intestinal microecology and immune response profile of the silkworm Bombyx mori strain Dazao after disinfectant exposure by using high-throughput sequencing technology and real-time PCR analysis. After egg surface sterilization, no significant difference (P > 0.05) in overall body weight was observed among the control, sodium hypochlorite, and formaldehyde groups. 16S rRNA metagenomic sequencing revealed that the main abundant intestinal bacteria were Enterococcus, Burkholderia, Phenylobacterium, Ralstonia, Chitinophaga, Bradyrhizobium, Herbaspirillum, and two unclassified Bacteroidetes species. Egg surface sterilization evidently altered the composition and abundance of intestinal microbiota but did not significantly change its alpha diversity. The dysbiosis of intestinal microbiota resulted in the perturbation of the immune response profile of the silkworm intestine. Our findings reveal that hypochlorite has a blocking effect on the symbiont transmission compared with formaldehyde. More importantly, egg surface sterilization exerts substantial effects on the ecophysiological traits of insects. The present study contributes to the scientific and reasonable application of disinfectants for insect egg surface sterilization during industrial silk production and laboratory-scale insect rearing.

Parental occupational exposures in wood-related jobs and risk of testicular germ cell tumours in offspring in NORD-TEST a registry-based case-control study in Finland, Norway, and Sweden

OBJECTIVE

We assessed the association between parental prenatal exposures in wood-related jobs and risk of testicular germ cell tumours (TGCT) in offspring.

METHODS

NORD-TEST, a registry-based case-control study in Sweden, Finland and Norway, included 8112 TGCT cases diagnosed at ages 14-49 years between 1978 and 2012 with no history of prior cancer, and up to four controls matched to each case on year and country of birth. Parents of cases and controls were identified via linkages with the population registries and their occupational information was retrieved from censuses. The Nordic Occupational Cancer Study Job-Exposure Matrix was used to assign occupational exposures to each parent. Logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Maternal wood-related job was not associated with the risk of TGCT in offspring (OR 1.08, CI 0.55-2.14), while paternal wood-related job was associated with a decreased risk of TGCT in offspring (OR 0.85, CI 0.75-0.96). None of the specific wood-related jobs, such as upholsterers, sawyers, or construction carpenters, were significantly associated with a risk of TGCT. Only exception was observed in a sensitivity analysis which showed an increased risk in the small group of sons of fathers working as 'cabinetmakers and joiners' the year before conception (OR of 2.06, CI 1.00-4.25).

CONCLUSION

This large-scale NORD-TEST analysis provided no evidence of an association between parental prenatal exposures in wood-related jobs and TGCT in sons.

Indoor and outdoor air pollution and couple fecundability: a systematic review

BACKGROUND

Air pollution is both a sensory blight and a threat to human health. Inhaled environmental pollutants can be naturally occurring or human-made, and include traffic-related air pollution (TRAP), ozone, particulate matter (PM) and volatile organic compounds, among other substances, including those from secondhand smoking. Studies of air pollution on reproductive and endocrine systems have reported associations of TRAP, secondhand smoke (SHS), organic solvents and biomass fueled-cooking with adverse birth outcomes. While some evidence suggests that air pollution contributes to infertility, the extant literature is mixed, and varying effects of pollutants have been reported.

OBJECTIVE AND RATIONALE

Although some reviews have studied the association between common outdoor air pollutants and time to pregnancy (TTP), there are no comprehensive reviews that also include exposure to indoor inhaled pollutants, such as airborne occupational toxicants and SHS. The current systematic review summarizes the strength of evidence for associations of outdoor air pollution, SHS and indoor inhaled air pollution with couple fecundability and identifies gaps and limitations in the literature to inform policy decisions and future research.

SEARCH METHODS

We performed an electronic search of six databases for original research articles in English published since 1990 on TTP or fecundability and a number of chemicals in the context of air pollution, inhalation and aerosolization. Standardized forms for screening, data extraction and study quality were developed using DistillerSR software and completed in duplicate. We used the Newcastle-Ottawa Scale to assess risk of bias and devised additional quality metrics based on specific methodological features of both air pollution and fecundability studies.

OUTCOMES

The search returned 5200 articles, 4994 of which were excluded at the level of title and abstract screening. After full-text screening, 35 papers remained for data extraction and synthesis. An additional 3 papers were identified independently that fit criteria, and 5 papers involving multiple routes of exposure were removed, yielding 33 articles from 28 studies for analysis. There were 8 papers that examined outdoor air quality, while 6 papers examined SHS exposure and 19 papers examined indoor air quality. The results indicated an association between outdoor air pollution and reduced fecundability, including TRAP and specifically nitrogen oxides and PM with a diameter of ≤2.5 µm, as well as exposure to SHS and formaldehyde. However, exposure windows differed greatly between studies as did the method of exposure assessment. There was little evidence that exposure to volatile solvents is associated with reduced fecundability.

WIDER IMPLICATIONS

The evidence suggests that exposure to outdoor air pollutants, SHS and some occupational inhaled pollutants may reduce fecundability. Future studies of SHS should use indoor air monitors and biomarkers to improve exposure assessment. Air monitors that capture real-time exposure can provide valuable insight about the role of indoor air pollution and are helpful in assessing the short-term acute effects of pollutants on TTP.

Ambient formaldehyde and mortality: A time series analysis in China

The potential health impact of low-level ambient formaldehyde has been historically overlooked. We conducted a two-stage time series analysis to investigate associations between ambient formaldehyde and daily nonaccidental, circulatory, and respiratory mortality and six subtypes based on 5,325,585 deaths in 275 Chinese counties between 2013 and 2018 and estimated a concentration-response curve to identify overall associations. After controlling for confounders from meteorological factors, air pollutants, time trend, and day of the week effect, with a 1-part per billion (ppb) increase in the daily concentration of formaldehyde on lag0 day, we found that mortality risks in nonaccidental, circulatory, and respiratory diseases increased by 0.36%, 0.36% and 0.41%, respectively. The curve indicated a possible threshold concentration at approximately 5 ppb for significant impact on nonaccidental and circulatory diseases. We suggest that ambient formaldehyde may represent a potential threat to public health and needs further investigation to support timely pollution regulation and health protection.

Approaches to Formaldehyde Measurement: From Liquid Biological Samples to Cells and Organisms

Formaldehyde (FA) is the simplest aldehyde present both in the environment and in living organisms. FA is an extremely reactive compound capable of protein crosslinking and DNA damage. For a long time, FA was considered a “biochemical waste” and a by-product of normal cellular metabolism, but in recent decades the picture has changed. As a result, the need arose for novel instruments and approaches to monitor and measure not only environmental FA in water, cosmetics, and household products, but also in food, beverages and biological samples including cells and even organisms. Despite numerous protocols being developed for in vitro and in cellulo FA assessment, many of them have remained at the “proof-of-concept” stage. We analyze the suitability of different methods developed for non-biological objects, and present an overview of the recently developed approaches, including chemically-synthesized probes and genetically encoded FA-sensors for in cellulo and in vivo FA monitoring. We also discuss the prospects of classical methods such as chromatography and spectrophotometry, and how they have been adapted in response to the demand for precise, selective and highly sensitive evaluation of FA concentration fluctuations in biological samples. The main objectives of this review is to summarize data on the main approaches for FA content measurement in liquid biological samples, pointing out the advantages and disadvantages of each method; to report the progress in development of novel molecules suitable for application in living systems; and, finally, to discuss genetically encoded FA-sensors based on existing natural biological FA-responsive elements.

Contribution of Aldehydes and Their Derivatives to Antimicrobial and Immunomodulatory Activities

Essential oils (EOs) are intricate combinations of evaporative compounds produced by aromatic plants and extracted by distillation or expression. EOs are natural secondary metabolites derived from plants and have been found to be useful in food and nutraceutical manufacturing, perfumery and cosmetics; they have also been found to alleviate the phenomenon of antimicrobial resistance (AMR) in addition to functioning as antibacterial and antifungal agents, balancing menstrual cycles and being efficacious as an immune system booster. Several main aldehyde constituents can be found in different types of EOs, and thus, aldehydes and their derivatives will be the main focus of this study with regard to their antimicrobial, antioxidative, anti-inflammatory and immunomodulatory effects. This brief study also explores the activity of aldehydes and their derivatives against pathogenic bacteria for future use in the clinical setting.

Association between maternal exposure to indoor air pollution and offspring congenital heart disease: a case–control study in East China

Background

Previous research suggested an association between maternal exposure to ambient air pollutants and the risk of congenital heart disease (CHD). However, the effect of individual prenatal exposure to indoor air pollutants on CHD occurrence was not reported.

Methods

We performed a hospital-based case–control study to investigate the association between personal air pollution exposure during pregnancy and the risk of CHD in offspring. A total of 44 cases and 75 controls were included from two hospitals in East China. We investigated maternal and residential environmental characteristics using a questionnaire and obtained personal indoor air samples to assess particulate matter (PM) and volatile organic compounds (VOCs) from 22–30 gestational weeks. Formaldehyde, benzene, toluene, xylene, total volatile organic compounds (TVOCs), PM_2.5, and PM₁₀ were assessed. Logistic regression was performed to assess associations and interactions between individual indoor air pollutants and CHD after adjusting for confounders. The potential residential environmental factors affecting the risks of indoor air pollutants on CHD were also assessed.

Results

Median TVOC (0.400 vs. 0.005 mg/m³, P < 0.001) exposure levels in cases were significantly higher than controls. A logistic regression model adjusted for confounders revealed that exposure to high levels of indoor TVOCs (AOR 7.09, 95% CI 2.10–23.88) during pregnancy was associated with risks for CHD and the occurrence of some major CHD subtype in offspring. These risk effects were enhanced in pregnant women living in a newly renovated house but were mitigated by household use of smoke ventilators when cooking. We observed a positive interaction of maternal exposure to TVOCs and PM_2.5 and the risk for CHD.

Conclusions

Maternal exposure to indoor VOCs and PMs may increase the risk of giving birth to foetuses with CHD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13174-0.

The exposure to formaldehyde in industries and health care centers: A systematic review and probabilistic health risk assessment

Formaldehyde is classified as a definitive human carcinogen by the International Agency for Research on Cancer (IARC). The workers in several industries such as foundry, melamine, resin, and health care centers (pathology and anatomy laboratories and operating rooms) are exposed to airborne formaldehyde. In this systematic review, studies conducted from 2000 to 2020 on occupational exposure to airborne formaldehyde in Iran were collected and analyzed. The carcinogenic and non-carcinogenic risk assessments of exposure to airborne formaldehyde were estimated using the recommended United State Environmental Protection Agency (USEPA) method by Monte-Carlo simulation. Results demonstrated that in both health care centers and industrial settings, mean concentrations of airborne formaldehyde were higher than that 8- hour time-weighted average threshold limit value (TWA-TLV) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). Also, results showed that cancer and non-cancer risks due to exposure to airborne formaldehyde (Neurological, dermal, respiratory effects and so on) were considerable in both industrial settings and health care settings. The results of this study could be used by health policy makers to eliminate or reduce exposure to airborne formaldehyde in workplaces.

ADH2/GSNOR1 is a key player in limiting genotoxic damage mediated by formaldehyde and UV-B in Arabidopsis

Maintenance of genome stability is an essential requirement for all living organisms. Formaldehyde and UV-B irradiation cause DNA damage and affect genome stability, growth and development, but the interplay between these two genotoxic factors is poorly understood in plants. We show that Arabidopsis adh2/gsnor1 mutant, which lacks alcohol dehydrogenase 2/S-nitrosoglutathione reductase 1 (ADH2/GSNOR1), are hypersensitive to low fluence UV-B irradiation or UV-B irradiation-mimetic chemicals. Although the ADH2/GSNOR1 enzyme can act on different substrates, notably on S-hydroxymethylglutathione (HMG) and S-nitrosoglutathione (GSNO), our study provides several lines of evidence that the sensitivity of gsnor1 to UV-B is caused mainly by UV-B-induced formaldehyde accumulation rather than other factors such as alteration of the GSNO concentration. Our results demonstrate an interplay between formaldehyde and UV-B that exacerbates genome instability, leading to severe DNA damage and impaired growth and development in Arabidopsis, and show that ADH2/GSNOR1 is a key player in combating these effects.

Tunable formaldehyde sensing properties of palladium cluster decorated graphene

The ability to tune the adsorption strength of the targeted gas on sensing materials is crucial for sensing applications. By employing first-principles calculations the adsorption and sensing properties of HCHO on small Pd _n (n = 1-6) cluster decorated graphene have been systematically investigated. The adsorption energy is found to depend on the size of the Pd _n cluster and can be tuned in a wide range from -0.68 eV on Pd(111) to -1.98 eV on the Pd₃/graphene system. We also find that the Pd _n /graphene (n = 5 and 6) systems have an appropriate adsorption energy for HCHO gas sensing. The current-voltage curves are calculated by the non-equilibrium Green's function method for the two-probe nano-sensor devices along both the armchair and zigzag directions. The devices constructed with Pd _n /graphene (n = 5 and 6), having the highest absolute response over 20% at small voltages, should be applicable for HCHO detection. This work provides a theoretical basis for exploring potential applications of metal cluster decorated graphene for gas sensing.

Associations between prenatal exposure to volatile organic compounds and neurodevelopment in 12-month-old children: The Japan Environment and Children's Study (JECS)

In recent years, there has been an increase in the number of problems associated with neurodevelopmental disorders in children, and there has been a growing interest in the relationship between environmental chemicals and children's health. The objective of this study was to examine whether an association exists between occupational or environmental prenatal maternal exposure to volatile organic compounds and the risk of neurodevelopmental disorders in children using Japanese translations of the Ages & Stages Questionnaires, Third Edition (J-ASQ-3). An increase in the risk of neurodevelopmental delay in 12-month-old children associated with maternal exposure to formalin or formaldehyde was identified in terms of problem-solving (odds ratio (OR): 1.76, 95% confidence interval (CI): 0.99-3.12) and personal-social skills (OR: 3.32, 95% CI: 1.46-7.55). It is not clear whether or not this tendency is reversible, and whether it is observed past 12 months of age. Further research and a preventive approach are needed.

Circular RNA-CDR1as is involved in lung injury induced by long-term formaldehyde inhalation

OBJECTIVE

Formaldehyde (FA) is known to induce lung injury, but the underlying molecular mechanism remains largely unclear. CDR1as is an important member of the circular RNAs (circRNAs) family and functions as miRNA sponges with gene-regulatory potential. Our earlier circRNA microarray data showed CDR1as was highly expressed in lung tissue exposed to FA. However, the mechanism of circRNA-CDR1as mediates the FA-exposed lung injury is still unclear. This study aimed to explore the role of CDR1as in lung injury.

MATERIALS AND METHODS

In this study, FA was inhaled at doses of 0.5, 2.46, and 5 mg/m3, respectively. After exposure 8 weeks, lung histopathological examination, lung injury score, and IL-1β in bronchoalveolar lavage fluid (BALF) were determined. The expressions of CDR1as, rno-miR-7b and Atg7 were detected and the potential interaction of circRNA/miRNA/mRNA was predicted by bioinformatics analysis, including drawing circRNA/miRNA/mRNA interaction network, GO and KEGG analysis.

RESULTS

Our results indicated FA inhalation upregulated the expression of CDR1as in lung tissues in a dose-dependent manner while the expression of rno-miR-7b decreased and Atg7 increased. Moreover, the alteration of CDR1as was positively correlated with lung injury.

DISCUSSION AND CONCLUSIONS

CircRNA/miRNA/mRNA prediction further explained the possible effect mechanisms of CDR1as. These data implicated that CDR1as might be a critical regulator involved in lung injury induced by FA.

Formaldehyde induces ferritinophagy to damage hippocampal neuronal cells

Formaldehyde (FA) causes neurotoxicity and contributes to the occurrence of neurodegenerative diseases. However, the mechanism of FA-induced neurotoxicity has not been fully elucidated. Ferritinophagy, an autophagy process of ferritin mediated by the nuclear receptor coactivator 4 (NCOA4), is a potential mechanism of neurotoxicity. In this study, we explored whether ferritinophagy is associated with the neurotoxicity of FA. Our results showed that FA (50, 100, 200 μM; 24 h) exposure upregulated ferritinophagy in the mouse hippocampal neuronal HT22 cells, which was evidenced by the upregulated autophagic flux, the increased colocalizations of NCOA4 with ferritin heavy chain (FTH1) and NCOA4 with microtubule-associated protein 1 light chain-3B (LC3B), the augmented expression of NCOA4, and the reduced content of FTH1. We also found that FA (0.1, 1, and 10 μmol, i.c.v., 7d) administration boosted ferritinophagy in the hippocampus of Sprague-Dawley (SD) rats, which was demonstrated by the accumulated autophagosomes, the increased expressions of LC3II/I and NCOA4, and the decreased contents of p62 and FTH1 in the hippocampus. Further, we confirmed that inhibition of ferritinophagy by silencing the expression of NCOA4 decreased FA-induced toxic damage in HT22 cells. These results indicated that FA induces neurotoxicity by promoting ferritinophagy. Our findings suggest a potential mechanism insight into the FA-induced neurotoxicity, which in turn provides a new thought for the treatment of FA-related neurodegenerative diseases.

A Roadmap for Navigating Occupational Exposures for Surgeons: A Special Consideration for the Pregnant Surgeon

SUMMARY

Surgeons are exposed to occupational hazards daily. Risks include chemical, biological, and physical hazards that place providers at risk of serious harm. Departmental policies or written guides to help pregnant surgeons navigate the hospital are lacking. In response to the scarcity in the literature, the authors have summarized current guidelines and recommendations to aid surgeons in making an informed decision. In addition, the authors present a brief narrative of the impact of these exposures during pregnancy and methods of transmission and, where relevant, include specialties that are at risk of these exposures.

Spraying Hatching Eggs with Clove Essential Oil Does Not Compromise the Quality of Embryos and One-Day-Old Chicks or Broiler Performance

Simple Summary

Studies on natural sanitizers for potentially safe hatching of eggs are essential. In this context, the objective of this study was to evaluate whether sanitizing hatching eggs with clove essential oil in the preincubation phase affects broiler performance (body weight, body weight gain, feed consumption, feed conversion ratio, and survivability). Furthermore, the effects of the oil on the hatch window and quality of embryos and one-day-old chicks were investigated. In this study, clove essential oil did not compromise the quality of the birds or the post-hatch performance.

Abstract

The objective of this study was to evaluate whether sanitizing hatching eggs with clove essential oil in the preincubation phase affects broiler performance and influences the hatch window and quality of embryos and one-day-old chicks. Hatching eggs (n = 1280; mean weight = 58.64 ± 0.49 g) from a batch of 37-week-old broiler breeder hens of the CPK (Pesadão Vermelho) lineage were randomly distributed into four treatments in the preincubation phase. The treatments consisted of three different sanitization procedures (spraying with grain alcohol, spraying with clove essential oil, and fumigation with paraformaldehyde) and a control treatment (nonsanitized). The lengths of the embryos and one-day-old chicks (one of the parameters used to assess bird quality) were not significantly different among the treatments, with means of 15.30 ± 1.41 and 18.37 ± 0.76 mm, respectively. Body weight, body weight gain, feed consumption, and feed conversion rate in different rearing periods did not differ significantly among the treatments. However, there was a significant difference in the percentage of survivability during the initial period (1 to 28 days) among the treatments. In conclusion, clove essential oil treatment did not negatively affect the quality of embryos and one-day-old chicks or the performance of broilers.

Review: Vaccine Myth-Buster - Cleaning Up With Prejudices and Dangerous Misinformation

Although vaccines have already saved and will continue to save millions of lives, they are under attack. Vaccine safety is the main target of criticism. The rapid distribution of false information, or even conspiracy theories on the internet has tremendously favored vaccine hesitancy. The World Health Organization (WHO) named vaccine hesitancy one of the top ten threats to global health in 2019. Parents and patients have several concerns about vaccine safety, of which the ubiquitous anxieties include inactivating agents, adjuvants, preservatives, or new technologies such as genetic vaccines. In general, increasing doubts concerning side effects have been observed, which may lead to an increasing mistrust of scientific results and thus, the scientific method. Hence, this review targets five topics concerning vaccines and reviews current scientific publications in order to summarize the available information refuting conspiracy theories and myths about vaccination. The topics have been selected based on the author's personal perception of the most frequently occurring safety controversies: the inactivation agent formaldehyde, the adjuvant aluminum, the preservative mercury, the mistakenly-drawn correlation between vaccines and autism and genetic vaccines. The scientific literature shows that vaccine safety is constantly studied. Furthermore, the literature does not support the allegations that vaccines may cause a serious threat to general human life. The author suggests that more researchers explaining their research ideas, methods and results publicly could strengthen the general confidence in science. In general, vaccines present one of the safest and most cost-effective medications and none of the targeted topics raised serious health concerns.

Formaldehyde and Brain Disorders: A Meta-Analysis and Bioinformatics Approach

While there is significant investigation and investment in brain and neurodegenerative disease research, current understanding of the etiologies of illnesses like Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and brain cancer remains limited. Environmental exposure to the pollutant formaldehyde, an emerging neurotoxin widely used in industry, is suspected to play a critical role in mediating these disorders, although findings are limited and inconsistent. Focusing on highly exposed groups, we performed a meta-analysis of human epidemiological studies of formaldehyde and neurodegenerative disease (N =  19) or brain tumors (N = 12). To assess the biological plausibility of observed associations, we then conducted a bioinformatics analysis using WikiPathways and the Comparative Toxicogenomics Database and identified candidate genes and pathways that may be related to these interactions. We reported the meta-relative risk (meta-RR) of ALS following high exposures to formaldehyde was increased by 78% (meta-RR = 1.78, 95% confidence interval, CI 1.20-2.65). Similarly, the meta-RR for brain cancer was increased by 71% (meta-RR = 1.71; 95% CI 1.07-2.73) among highly exposed individuals. Multiple sensitivity analyses did not reveal sources of heterogeneity or bias. Our bioinformatics analysis revealed that the oxidative stress genes superoxide dismutase (SOD1, SOD2) and the pro-inflammatory marker tumor necrosis factor (TNF) were identified as the top relevant genes, and the folate metabolism, vitamin B12 metabolism, and the ALS pathways were highly affected by formaldehyde and related to the most brain diseases of interest. Further inquiry revealed the two metabolic pathways are also intimately tied with the formaldehyde cycle. Overall, our bioinformatics analysis supports the link of formaldehyde exposure to ALS or brain tumor reported from our meta-analysis. This new multifactorial approach enabled us to both interrogate the robustness of the epidemiological data and identify genes and pathways that may be involved in these interactions, ultimately lending strong evidence and potential biological plausibility for the association between formaldehyde exposure and brain disease.

Using a safe and effective fixative to improve the immunofluorescence staining of bacteria

The emerging and development of green chemistry has once again drawn the researchers' attention to eliminating the use and generation of hazardous materials. Here we report the use of a safe and effective fixative, chlorine dioxide (ClO₂), instead of traditional hazardous fixatives for the cross-linking of cellular proteins to improve immunofluorescence staining of bacteria. The concentration of ClO₂needed for 100% fixation is 50μg ml^-1, which is much lower than that of traditional fixatives (1000-10000μg ml^-1). The ClO₂mediated cross-linking can preserve the integrity of bacterial cells and prevent cell loss through lysis. Meanwhile, lysozyme can permeabilize the bacterial cells, allowing the labelled antibodies to diffuse to their intracellular target molecules. By usingE. coliO157:H7/RP4 as a gram-negative bacteria model, immunofluorescence staining assays for both intracellular protein and surface polysaccharide were carried out to investigate the effect of ClO₂fixation on the staining. The results demonstrated that ClO₂fixation could prevent the target antigens from cracking off the bacteria without damage on the interaction between the antibodies and antigens (either for polysaccharide or protein). As a safe and effective fixative, ClO₂has potential practical applications in immunofluorescence staining and fluorescencein situhybridization for single bacteria/cell analysis.

Applying genome-wide CRISPR to identify known and novel genes and pathways that modulate formaldehyde toxicity

Formaldehyde (FA), a ubiquitous environmental pollutant, is classified as a Group I human carcinogen by the International Agency for Research on Cancer. Previously, we reported that FA induced hematotoxicity and chromosomal aneuploidy in exposed workers and toxicity in bone marrow and hematopoietic stem cells of experimental animals. Using functional toxicogenomic profiling in yeast, we identified genes and cellular processes modulating eukaryotic FA cytotoxicity. Although we validated some of these findings in yeast, many specific genes, pathways and mechanisms of action of FA in human cells are not known. In the current study, we applied genome-wide, loss-of-function CRISPR screening to identify modulators of FA toxicity in the human hematopoietic K562 cell line. We assessed the cellular genetic determinants of susceptibility and resistance to FA at 40, 100 and 150 μM (IC10, IC20 and IC60, respectively) at two time points, day 8 and day 20. We identified multiple candidate genes that increase sensitivity (e.g. ADH5, ESD and FANC family) or resistance (e.g. FASN and KDM6A) to FA when disrupted. Pathway analysis revealed a major role for the FA metabolism and Fanconi anemia pathway in FA tolerance, consistent with findings from previous studies. Additional network analyses revealed potential new roles for one-carbon metabolism, fatty acid synthesis and mTOR signaling in modulating FA toxicity. Validation of these novel findings will further enhance our understanding of FA toxicity in human cells. Our findings support the utility of CRISPR-based functional genomics screening of environmental chemicals.

Formaldehyde-induced hematopoietic stem and progenitor cell toxicity in mouse lung and nose

Formaldehyde (FA), an economically important and ubiquitous chemical, has been classified as a human carcinogen and myeloid leukemogen. However, the underlying mechanisms of leukemogenesis remain unclear. Unlike many classical leukemogens that damage hematopoietic stem/progenitor cells (HSC/HPC) directly in the bone marrow, FA-as the smallest, most reactive aldehyde-is thought to be incapable of reaching the bone marrow through inhalation exposure. A recent breakthrough study discovered that mouse lung contains functional HSC/HPC that can produce blood cells and travel bi-directionally between the lung and bone marrow, while another early study reported the presence of HSC/HPC in rat nose. Based on these findings, we hypothesized that FA inhalation could induce toxicity in HSC/HPC present in mouse lung and/or nose rather than in the bone marrow. To test this hypothesis, we adapted a commercially available protocol for culturing burst-forming unit-erythroid (BFU-E) and colony-forming unit-granulocyte, macrophage (CFU-GM) colonies from bone marrow and spleen to also enable culture of these colonies from mouse lung and nose, a novel application of this assay. We reported that in vivo exposure to FA at 3 mg/m3 or ex vivo exposure up to 400 µM FA decreased the formation of both colony types from mouse lung and nose as well as from bone marrow and spleen. These findings, to the best of our knowledge, are the first empirically to show that FA exposure can damage mouse pulmonary and olfactory HSC/HPC and provide potential biological plausibility for the induction of leukemia at the sites of entry rather than the bone marrow.

Autopsy, thanatopraxy, cemeteries and crematoria as hotspots of toxic organic contaminants in the funeral industry continuum

The occurrence and health risks of toxic organic contaminants (TOCs) in the funeral industry are relatively under-studied compared to other industries. An increasing body of literature reports TOCs including emerging contaminants in the funeral industry, but comprehensive reviews of the evidence are still lacking. Hence, evidence was analysed to address the proposition that, the funeral industry constitutes several hotspot reservoirs of a wide spectrum of TOCs posing ecological and human health risks. TOCs detected include embalming products, persistent organic pollutants, synthetic pesticides, pharmaceuticals, personal care products and illicit drugs. Human cadavers, solid wastes, wastewaters and air-borne particulates from autopsy, thanatopraxy care facilities (mortuaries, funeral homes), cemeteries and crematoria are hotspots of TOCs. Ingestion of contaminated water, and aquatic and marine foods constitutes non-occupational human exposure, while occupational exposure occurs via inhalation and dermal intake. Risk factors promoting exposure to TOCs include unhygienic burial practices, poor solid waste and wastewater disposal, and weak and poorly enforced regulations. The generic health risks of TOCs are quite diverse, and include; (1) genotoxicity, endocrine disruption, teratogenicity and neurodevelopmental disorders, (2) development of antimicrobial resistance, (3) info-disruption via biomimicry, and (4) disruption of ecosystem functions and trophic interactions. Barring formaldehyde and inferential evidence, the epidemiological studies linking TOCs in the funeral industry to specific health outcomes are scarce. The reasons for the lack of evidence, and limitations of current health risk assessment protocols are discussed. A comprehensive framework for hazard identification, risk assessment and mitigation (HIRAM) in the funeral industry is proposed. The HIRAM includes regulatory, surveillance and control systems such as prevention and removal of TOCs. Future directions on the ecotoxicology of mixtures, behaviour, and health risks of TOCs are highlighted. The opportunities presented by emerging tools, including isotopic labelling, genomics, big data analytics (e.g., machine learning), and in silico techniques in toxicokinetic modelling are highlighted.

Toxic effects of formaldehyde and the protective effect of docosahexaenoic acid in Drosophila

Formaldehyde (FA) is a commercially important chemical applied in industry and scientific research. However, FA has a distinct impact on learning and memory. Although the mechanisms of FA toxicity have been well studied, additional research is required to establish the mechanisms of neuroprotection in cases of FA exposure. Docosahexaenoic acid (DHA) is a polyunsaturated fatty acid with a variety of health benefits, including the enhancement of learning and memory. In this study, we investigated the neuroprotective effects of DHA in Drosophila melanogaster that had ingested FA. Our data suggested that DHA enhanced reproductive processes, leading to an increase in the number of eggs, larvae, and adults. Surprisingly, we found that DHA had a mild protective effect against FA-induced impairments in learning and memory.

Long-term exposure to formaldehyde induced down-regulation of SPO11 in rats

Objective: Formaldehyde, a ubiquitous environmental contaminant, has long been suspected of causing male reproductive injury, but the underlying molecular mechanism remains largely unknown. SPO11 is a meiosis-related gene, whose absence can cause spermatogenesis arrest. Materials and methods: The present study aimed to explore the role of SPO11 in male reproductive injury induced by long-term formaldehyde exposure, so as to further understand the molecular mechanism of formaldehyde-induced male reproductive toxicity. Adult male Sprague-Dawley rats (n = 24, 245 ± 22 g) were randomly divided into four groups of six (n = 6) and were exposed to formaldehyde gas at doses of 0 (control), 0.5, 2.46 and 5 mg/m³, respectively, via inhalation for 8 consecutive weeks. Results and dissussion: The expression levels of SPO11 were detected in testicular tissues by real-time quantitative polymerase chain reaction, immunofluorescence, and Western blot. The results indicated that the expression of SPO11 was inhibited by formaldehyde exposure in a dose-dependent manner. Furthermore, the histopathological results showed that testicular seminiferous tubules were atrophied, spermatogenic cells were decreased and the lumina were oligozoospermic in the 2.46 and 5 mg/m³ formaldehyde exposure groups. Combined with the morphometric results, we found that the downregulated expression levels of SPO11 were consistent with the changes of testicular seminiferous tubule diameter and seminiferous epithelium height in testicular tissue, suggesting that SPO11 might be one of the main targets of formaldehyde reproductive toxicity. Conclusions: In conclusion, our findings indicated that SPO11 might be related to male reproductive injuries induced by long-term formaldehyde exposure.